Eco-friendly weed control in lawns

By Melinda Myers
Special to the Journal

Don’t let lawn weeds get the best of you. These opportunistic plants find a weak spot in the lawn, infiltrate and begin to take over your grass. Take back the lawn with proper care.  Your lawn will not only be greener and healthier, but good for the environment.
The grass and thatch layer act as a natural filter, helping to keep pollutants out of our groundwater and dust out of our atmosphere. They also reduce erosion, decrease noise and help keep our homes and landscapes cooler in summer. And a healthy lawn is the best defense against weeds.
Start by identifying the unwanted lawn invaders. Use them as a guide to improve your lawn’s health and beauty. Weeds appear and spread when the growing conditions are better for them than the grass. Correct the problem to reduce the weeds and improve the health of your lawn. Killing the weeds without fixing the underlying cause is only a temporary solution. Unless the cause is eliminated the weed problem will return.
Here are a few of the more common weeds, the cause and possible solutions for managing them out of the lawn.
High populations and a variety of weeds mean you need to adjust your overall lawn care practices. Mow high and often, removing no more than 1/3 the total height of the grass at one time. Leave the clippings on the lawn in order to return water, nutrients and organic matter to the soil. This along with proper fertilization using an organic nitrogen slow release fertilizer with non leaching phosphorous, like Milorganite (milorganite.com), can greatly reduce weeds.
Knotweed and plantains often found growing next to walks and drives or other high traffic areas can also be found in lawns growing on heavy poorly prepared soils. These weeds thrive in compacted soil where lawn grasses fail. Reduce soil compaction and improve your lawn’s health with core aeration.  Aerate lawns when actively growing in spring or fall. Or replace grass in high traffic areas with permeable pavers or stepping stones to eliminate the cause.
Nut sedge is a common weed in wet or poorly drained soils. Improve the drainage to manage this weed. It may mean core aerating the lawn and topdressing with compost, regrading or the installation of a rain garden to capture, filter and drain excess water back into the ground.
Clover and black medic mean it’s time to get the soil tested and adjust fertilization.  Both thrive when the lawn is starving. Clover was once included in lawn mixes because of its ability to capture nitrogen from the atmosphere and add it to the soil.  If these weeds are present, boost the lawn’s diet starting this spring with a low nitrogen slow release fertilizer. It feeds slowly throughout the season, promoting slow steady growth that is more drought tolerant, disease resistant and better able to outcompete the weeds.
Creeping Charley, also known as ground ivy, violets, and plantains usually get their foothold in the shade and then infiltrate the rest of the lawn. Take back those shady spots by growing a more shade tolerant grass like the cool season grass fescue or warm season St. Augustine grass. Mow high and fertilize less, only 1 to 2 pounds of nitrogen per growing season, than the sunny areas of your lawn. Or replace the lawn with shade tolerant groundcovers. Adjust your overall care to reclaim and maintain the rest of the lawn.
Crabgrass and Goosegrass are common weeds that follow a hot dry summer. Mow high to shade the soil and prevent many of these annual grass weeds from sprouting. Corn gluten meal is an organic pre-emergent weed killer that can help reduce these and other weeds from sprouting. Apply in spring and fall applications to reduce weeds by as much as 80 percent in three years.
And, when mowing this year, consider an electric or push mower to manage your lawn in an even more eco-friendly manner.
Gardening expert, TV/radio host, author & columnist Melinda Myers has more than 30 years of horticulture experience and has written over 20 gardening books, including Can’t Miss Small Space Gardening and the Midwest Gardener’s Handbook. She hosts The Great Courses “How to Grow Anything” DVD series and the nationally syndicated Melinda’s Garden Moment segments. Myers is also a columnist and contributing editor for Birds & Blooms magazine. Myers’ web site, www.melindamyers.com, offers gardening videos and tips.